KONDO RESONANCE AND LOG-T CONDUCTIVITY IN HIGHLY CONDUCTING TRANSPOLYACETYLENE

The density of states of a U-impurity in a chain of trans-polyacetylen e is calculated as a function of the atomic impurity level and the hyb ridization energy. A residual gap in the density of states of the cond uction band is included. It is shown that a Kondo-like resonance exist s at the top of the gap and that a log T behavior should occur in the resistivity of the sample, as experiments have revealed. We demonstrat e that in order to observe the resonance, the gap must be smaller than the Kondo temperature in the gapless system.